When it comes to face masks, not all are equally effective, a new study finds.
Duke University researchers developed a way of testing various types of masks to see which did the best job of stopping droplets coming from people’s mouths, preventing spread of the new coronavirus.
They relied on a makeshift apparatus consisting of a box, a laser, a lens and a cellphone camera.
“We confirmed that when people speak, small droplets get expelled, so disease can be spread by talking, without coughing or sneezing,” said Martin Fischer, a chemist and physicist at the Durham, N.C., campus. “We could also see that some face coverings performed much better than others in blocking expelled particles.”
What masks do the best job? That would be N95 masks without valves, followed by surgical or polypropylene masks.
Handmade cotton masks also stop a lot of droplets from normal speech, researchers said.
But bandanas and neck fleeces like balaclavas didn’t block saliva spray much at all.
“This was just a demonstration — more work is required to investigate variations in masks, speakers, and how people wear them,” Fischer said in a university news release. He added it demonstrates that businesses and others that are providing masks to employees or patrons could do similar testing.
“If everyone wore a mask, we could stop up to 99% of these droplets before they reach someone else,” said Dr. Eric Westman, an associate professor of medicine at Duke. “In the absence of a vaccine or antiviral medicine, it’s the one proven way to protect others as well as yourself.”
The report was published online Aug. 7 in the journal Science Advances.
For more on COVID-19 face masks, visit the U.S. Centers for Disease Control and Prevention.
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